HIGH-DOSE IMPLANTATIONS OF AL INTO SI(111) AND SI(100)

High dose implants of Al (0.5 x 10(18)/cm2 to 2.0 x 10(18)/cm2) into s ilicon substrates (T(i) = 375-degrees-C) were performed in an attempt to form a pure, monocrystalline buried layer of Al in silicon upon pos t-implant annealing. Nuclear reaction analysis (NRA) and Auger electro n spectroscopy (AES) were used to determine the Al concentration and m orphology as a function of depth. The results show a peak Al concentra tion of 83 at.% at a depth of almost-equal-to 350 nm for the highest d ose, and the morphology of the Al is of an interconnected network of 1 00 at.% Al. The failure to form a continuous elemental layer is explai ned by the as-implanted morphology resulting from enhancement of the t hermally induced precipitate coarsening rate at 375-degrees-C. The for mation of large, stable, individual Al precipitates was thermodynamica lly favored for the implant conditions and effectively precluded coale scence into a continuous layer.